I would like to discuss a design idea around the supply of OpAmps that drive a ADC cannels of a microcontroller or DSP. Let the ADC be supplied by 3.3V and 0V ("analog" supplies separated from similar "digital" supplies), with an internal or external reference of 3.0V, that defines the full-scale input.
If the OpAmp is supplied by the same 3.3V - 0V, even if it is a rail-to-rail model, there is always a "footroom" limit of at least some tents of milliVolts. Therefore, my idea is to use a "Single Supply OpAmp" where its negative supply is connected to a slightly negative voltage, in order to use its complete voltage swing compensating for its rail-to-output difference both on the positive and the negative side of the amplifier.
What do you think about?